Andrew Sack

🏮 Another population-level study finds no evidence whatsoever of that healthy younger individuals given COVID-19 vaccines had increased risk of "dying suddenly", i.e. with sudden cardiac deaths. Researchers in Toronto just published a study in PLOS Medicine assessing whether risk of sudden cardiac death was increased after COVID-19 vaccination in healthy young people 12-50yrs old. The study was a population-based matched case-control study from a cohort of 14,966,193 residents of Ontario, Canada, focusing on the subset of 6,365,451 who were <50yrs and "healthy", with no medical history of cardiovascular disease, cancer, diabetes, mental illness, dementia, COPD, IBD, chronic liver or kidney disease, autoimmune disease, or alcohol or illicit drug use. Cases included 4,803 individuals from that cohort who "died suddenly" between April 1, 2021 and June 30, 2023, meaning they either died outside the hospital or died in ER or within 24hr of admission with indication of cardiac arrest, sudden death or arrhythmia but no indication of trauma, mental illness or substance use. Controls included 24,030 individuals matched 5:1 to cases in terms of age, sex, geographic area, and neighborhood income quintile, with their index data set to death date of matched case. After matching, all of these variables were well-balanced between cases and controls. The primary analysis was a conditional logistic regression to assess association of case/control status with vaccination status (any vaccine), with covariate-adjustment for confounders including COVID-19 infection, influenza vaccination, number of SARS-CoV-2 PCR tests to estimate COVID healthcare utilization, and history of asthma, hypertension and mood/anxiety disorders. Many sensitivity analyses were done including separate analyses for vaccine types, focusing on the 6wk period after vaccination, focusing only on ER/hospital deaths with cause well-documented, excluding any opioid deaths, focusing on <=40yrs old, plus a secondary self-controlled case series comparing the 6wk after doses 1/2/3 to other time periods to perform an assessment free from any subject-level residual confounders such as healthcare utilization or other factors related to healthy vaccinee effect. In the primary analysis, 77.1% of controls received any COVID-19 vaccine before the index date, while only 67.4% of cases did, which resulted in an adjusted odds ratio of 0.57 (95% CI 0.53-0.61), suggesting a 43% reduced risk of sudden death in the vaccinated group. All secondary analyses found similar results, with vaccinated having lower risk of sudden death than unvaccinated, with some statistically significant and some not. None of the analyses had any indication whatsoever that risk of sudden death was increased after vaccination, either in the short or long term. This validates results from two earlier UK studies using self-controlled case series that found no increased risk of sudden cardiac death within 4wks (Nafilyan et al. 2023 Nature Communications PMID: 36973247) or 12wks (Xu et al. 2024 Vaccine PMID: 38388239) after COVID-19 vaccination. So, in spite of all of the repeated claims on social media and in videos purporting major increased risk in sudden cardiac death after COVID-19 vaccination, the population-level data continue to strongly refute these claims.